Selective removal of tertiary base olefines



UNITED STATES FATE FFIE

SELECTIVE REMOVAL 0F TERTIARY BASE OLEFINES William Engs and Richard Moravec, Berkeley,

Calif., assignors to Shell Development Company, San Francisco, Calif, a corporation of This invention relates to a process for the segregation of highly reactive olefines from olefinic mixtures containing more than three carbon atoms to the molecule and is more particularly concerned with a continuous cyclic process which effects an economy in the necessary amount of selective agent required to selectively diminish the highly reactive olefine content.

Prior investigators have utilized olefine-containing fluids, such as those derived by the pyrogenetic treatment of peat petroleum, coal, oil shales and like carboniferous natural materials to produce secondary alcohols but very few have been concerned with the selective removal of highly reactive unsaturates prior to the formation of the desirable secondary alcohols.

We have discovered that secondary alcohols can be prepared simply and economically from olefine-containing fluids of the type mentioned heretofore by practicing the selective removal of highly reactive olefines in a preferably continuous manner wherein the selective agent is recovered and recycled for further use.

The preferred initial material is substantially stripped of hydrocarbons containing less than four carbon atoms to the molecule and suitably fractionated into fractions containing hydrocarbons of the same number of carbon atoms to the molecule. In certain instances, it will be difficult to remove traces of higher and lower carbon compounds, but their presence is not detrimental to this process. In certain other situations, it may be desirable to operate with a fraction containing a mixture of carbon compounds such as a 4 and 5 or a 5 and 6 or a 4, 5 and 6 carbon compound fraction and the like. We prefer to practice our process with a substantially pure fraction of hydrocarbons of which each molecule contains the same number of carbon atoms. In segregating the hydrocarbons into suitable fractions, it will be found that it will be practically impossible to separate the paraffin hydrocarbons from the olefine hydrocarbons possessing the same number of carbon atoms to the molecule without uneconomical and complicated procedure. As the parafiin hydrocarbons may be considered as inert compounds in our process, their presence in their corresponding carbon compound fraction is not accompanied by any detrimental effect.

The fractions to be treated are thus characteristically composed of paraffin hydrocarbons, olefines, both isoand normal, which yield secondary derivatives (hereinafter designated as secondary-base olefines) iso-olefines which yield tertiary derivatives (hereinafter designated as tertiary-base olefines) and traces of diolefines such as butadiene and isoprene.

For illustrative purposes only, references will be had to a substantially pure butane-butane fraction which represents a mixture of butane and butene obtained by distillation or condensation or both. Besides the butane there will be normally present isobutane, butene-l, butene-Z and isobutene. Isobutene is characteristic of the tertiary-base olefines as regards their high rates of reactivity with various reagents. It is preferable to selectively remove the isobutene content prior to the conversion of the secondary-base olefines to alkyl acid esters and/or secondary alcohols otherwise the tertiary-base olefines polymerizes, causing local overheating and thus decreasing the possible effective yields of secondary alcohols; or incomplete conversion of the secondary-base olefines results from the desire to avoid excessive polymerization of the tertiarybase olefine.

Selective agents for tertiary-base olefines are polybasic acids of which sulfuric acid or phosphoric acid are typical. In certain instances it may be desirable to employ monobasic acids such as hydrochloride acid or organic acids such as benzene sulfonic acids or the sulfonic acids of the homologues of benzene. These selective agents in a relatively heated condition polymerize the highly reactive olefines present in a hydrocarbon mixture without substantially affecting the secondary olefines present provided the time of contact is adjusted to the given acidity of the selective agent and to its thermal state.

The desired fraction, either in the gaseous or liquid state-the liquid state promoting increased surface contactfiis contacted with a relatively hot selective polymerizer in any suitable manner with or without pressure. For example, resort may be had to the agitation of the two agents in a common vessel or to counter-current flow. It is desirable when employing a fraction in the gaseous state to conduct the process in countercurrent fashion through a packed or bubble plate tower as this system lends itself most readily to intimate distribution of the tertiary-base olefine in the selective polymerizer. Care must be taken that the strengths of the selective polymerizers are regulated according to the temperature of the process, to the time of contact and according to the character of the tertiary-base olefine. In practicing our invention, we preferably employ sulfuric acid containing between and 75% I-I2S04, preferably -70% H2804 as it apparently yields the best results with fractions containing hydrocarbons possessing 4 or 5 carbon atoms to the molecule and the like.

We have found that 65% H2804 at -135 F. is sufiicient to polymerize substantially all the isobutene, the time of contact depending on the volume ratio of hydrocarbon and acid while butene-l and butcne-2 substantially do not polymerize but remain associated with the butane. Since the polymers of isobutene (and also of the other tertiary-base olefines) are hydrocarbons relatively immiscible with the selective polymerizer (in this example, sulfuric acid), they become associated with the butane, butene-l and butene-2 when the latter are in the liquid phase. A small proportion of the polymers may become emulsified or mixed with the acid liquor. The acid liquor and the hydrocarbon fraction in the liquid phase containing polymers tend to form two liquid phases which can be readily separated by gravity or the like; the acid liquor phase being at the bottom of the settling vessel.

The polymers contained in the acid liquor can be easily separated therefrom by any suitable operation known to the art, for example by gravity or by centrifuging. Alternatively, the polymers can be caused to separate from the acid liquor while the latter is coexistent or contiguous with the liquid hydrocarbon phase by agitation of the acid phase or by any conventional deemulsification method known to the art and the acid liquor subsequently removed for further use. If desired, the acid liquor phase subsequent to separation from the hydrocarbon phase and removal of polymers therefrom may be reheated for recycling with the same and/or further fractions or mixtures, being first adjusted to the proper strength and/or temperature prior to recycling. The liquid hydrocarbon phase which contains the tertiary olefines in a less reactive form (polymers) may be further worked up per se as by treatment with relatively strong acid to esterify the secondary olefine content or the polymer may first be removed. A simple method of separation of polymers from hydrocarbon is distillation.

Although we prefer to conduct the process in a continuous manner, the operation can be carried out as a batch or intermittent process as can be readily understood by any skilled chemist.

The polymers obtained may be admixed with hydrocarbon fuel to enhance the anti-knock rating of the latter.

The above operation can be conducted with fractions containing 5 carbon atoms or 6 carbon atoms to the molecule and the like. We have found that 70% H2804 at about F. is suificient to polymerize substantially all the tertiary amylene while the secondary amylenes substantially do not polymerize.

Thus by continuously introducing a selective polymerizer and a preferred hydrocarbon fraction in a suitable contact vessel, selectively polymerizing the tertiary-base olefine, removing the polymer from the liquid hydrocarbon phase, as by distillation, and continuously recovering and recycling the selective polymerizer, we have a closed, complete continuous process which furnishes a hydrocarbon fraction practically devoid of tertiary-base olefines, which yields a desirable anti-knock agent and which requires a minimum of selective polymerizer to operate, all tending towards a flexible, easily regulatable process which constitutes an advance in the art relating to the preparation of secondary alcohols.

When diolefines are present in the fraction undergoing treatment, they are selectively polymerized practically simultaneously with the tertiary-base olefines and are removed with the polymers of tertiary-base olefines.

It is to be understood that by operating with shorter periods of contact, the given acidity and/or temperature of any selective polymerizer may be safely increased and vice versa; the temperature varying inversely with the acidity and/ or the time factor.

While we have in the foregoing described in some detail the preferred embodiment of our invention and some variants thereof, it will be understood that this is only for the purpose of making the invention more clear and that the invention is not to be regarded as limited to the details of operation described, nor is it dependent upon the soundness or accuracy of the theories which we have advanced as to the reasons for the advantageous results attained. On the other hand, the invention is to be regarded as limited only by the terms of the accompanying claims, in which it is our intention to claim all novelty inherent therein as broadly as is possible in view of the prior art.

We claim as our invention:

1. The process of reacting a mixture of olefines with hot acid of an acid concentration and at a temperature whereby substantially all of the tertiary olefine content is polymerized without substantially polymerizing secondary olefines present, separating from the acid liquor a substantial proportion of the polymers present and then bringing the separated acid liquor into contact with an additional quantity of olefine.

2. The process of reacting a mixture of olefines with hot dilute acid of an acid concentration and at a temperature whereby substantially all of the tertiary olefine content is polymerized, without substantially polymerizing secondary olefines present, separating from the acid liquor a substantial proportion of the polymers present and then bringing the separated acid liquor into contact with an additional quantity of olefine.

3. The process of reacting a mixture of olefines with sulfuric acid of an acid concentration and at a temperature and for a time whereby substantially all of the tertiary olefine content is substantially instantaneously polymerized, without substantially polymerizing secondary olefines present and separating from the acid liquor a substantial proportion of the polymers present.

4. The process of reacting a mixture of olefines with dilute sulfuric acid of an acid concentration and at a temperature and for a time whereby substantially all of the tertiary olefine content is substantially instantaneously polymerized, without substantially polymerizing secondary olefines present and separating from the acid liquor a substantial proportion of the polymers present.

5. The process of reacting a mixture of olefines with acid of an acid concentration and at a temperature and for a time whereby substantially all of the tertiary olefine content is substantially instantaneously polymerized, without substantially polymerizing secondary olefines present and separating from the acid liquor a substantial proportion of the polymers present.

6. The process of reacting a mixture of olefines with hot acid of an acid concentration and at a temperature and for a time whereby substantially all of the tertiary olefine content is substantially instantaneously polymerized, without substantially polymerizing secondary olefines- V resent and separating from the acid liquor a substantial proportion of the polymers present.

7. The continuous process for the selective removal of tertiary-base olefines from hydrocarbon mixtures containing the same, comprising contacting the hydrocarbon mixture with an acid of given strength and at a temperature and for a time whereby substantially all of the tertiary olefine content is substantially instantaneously polymerized, without substantially polymerizing secondary olefines present, affecting the stratification of the acid mixture into an acid liquor phase and a hydrocarbon phase, separating the two phases and recovering polymer from both phases.

8. The continuous process for the selective removal of tertiary-base olefines from hydrocarbon mixtures containing the same, comprising contacting the hydrocarbon mixture with an acid of given strength and at a temperature and for a time whereby substantially all of the tertiary olefine content is substantially instantaneously polymerized, without substantially polymerizing secondary olefines present, affecting the stratification of the acid mixture into an acid liquor phase and a hydrocarbon phase, separating the two phases and recovering polymer from the hydrocarbon phase.

9. The continuous process for the selective removal of tertiary-base olefines from hydrocarbon mixtures containing the same, comprising contacting the hydrocarbon mixture with an acid of given strength and at a temperature and for a time whereby substantially all of the tertiary olefine content is substantially instantaneously polymerized, Without substantially polymerizing secondary olefines present, affecting the stratification of the acid mixture into an acid liquor phase and a hydrocarbon phase, separating the two phases and recovering polymer from the acid liquor phase.

10. The continuous process for the selective removal of tertiary-base olefines from hydrocarbon mixtures containing the same, comprising contacting the hydrocarbon mixture with an acid of given strength and at a temperature whereby substantially all the tertiary olefine content is polymerized, without substantially polymerizing secondary olefines present, .afiecting the stratification ot the acid mixture into an acid liquor phase and a hydrocarbon phase, separating the two phases, recovering polymer from the acid liquor phase and recycling the recovered acid so that it is contacted with fresh hydrocarbon mixtures containing tertiary-base olefines.

11. The continuous process for the selective removal of tertiary-base olefines from hydrocarbons containing the same, comprising contacting the hydrocarbon mixture with an acid of given strength and at a temperature whereby substantially all of the tertiary olefine content is polymerized without substantially polymerizing secondary olefines present, affecting the stratification of the acid mixture into an acid liquor phase and a hydrocarbon phase,- separating the two phases and recycling the acid liquor phase so that it is contacted with fresh hydrocarbon mixtures containing tertiary-base olefines.

12. The process for the selective removal of tertiary-base olefines from hydrocarbon mixtures containing paraffin and olefine hydrocarbons of the same number of carbon atoms to the molecule comprising reacting the hydrocarbon mixture with hot acid of an acid concentration and at a temperature whereby substantially all ofthe tertiary olefine content is polymerized, without substantially polymerizing secondary olefines present, separating from the acid liquor a substantial proportion of the polymers present and then bringing the separated acid liquor into contact with an additional quantity of olefine.

13. The process for the selective removal of tertiary-base olefines from hydrocarbon mixtures containing parafiin and olefine hydrocarbons of the same number of carbon atoms to the molecule comprising reacting the hydrocarbon mixture with hot dilute acid of an acid concentration and at a temperature whereby substantially all of the tertiary olefine content is polymerized, without substantially polymerizing secondary olefines present, separating from the acid liquor a substantial proportion of the polymers present and then bringing the separated acid liquor into contact with an additional quantity of olefine.

14. The process for the selective removal of tertiary-base olefines from hydrocarbon mixtures containing paraflin and olefine hydro-carbons of the same number of carbon atoms to the molecule comprising reacting the hydrocarbon mixture with sulfuric acid of an acid concentration and at a temperature and for a time whereby substantially all of the tertiary olefine content is substantially instantaneously polymerized, without substantially polymerizing sectertiary-base olefines from hydrocarbon mixtures containing paraffin and olefine hydrocarbons of the same number of carbon atoms to the molecule comprising reacting the hydrocarbon mixture with dilute sulfuric acid of an acid concentration and at a temperature and for a time whereby substantially all of the tertiary olefine content is substantially instantaneously polymerized, without substantially polymerizing secondary olefines present and separating from the acid liquor a substantial proportion of the po1ymers present.

16. The process for the selective removal of tertiary-base olefines from hydrocarbon mixtures containing paraffin and olefine hydrocarbons of the same number of carbon atoms to the molecule comprising reacting the hydrocarbon mixture with acid of an acid concentration and at a temperature and for a time whereby substantially all of the tertiary olefine content is substantially instantaneously polymerized. without substantially polymerizing secondary olefines present and separating from the acid liquor 'a substantial proportion of the polymers present.

17. The process for the selective removal of tertiary-base olefines from hydrocarbon mixtures containing parafiin and olefine hydrocarbons of the same number of carbon atoms to the molecule comprising reacting the hydrocarbon mixture of olefines with hot acid of an acid concentration and at a temperature and for a time whereby substantially all of the tertiary olefine content is substantially instantaneously polymerized, without substantially polymerizing secondary olefines present and separating from the acid liquor -a substantial proportion of the polymers present.

18. The process for the selective removal of tertiary-base olefines from hydrocarbon mixtures produced by cracking petroleum oil and containing paraffin and olefine hydrocarbons of the same number of carbon atoms to the molecule. comprising reacting the hydrocarbon mixture with hot acid of an acid concentration and at a temperature whereby substantially all of the tertiary clefine content is polymerized, without substantially polymerizing secondary olefines present, separating from the acid liquor a substantial proportion of the polymers present and then bringing the separated acid liquor into contact with an additional quantity of olefine.

19. The process for the selective removal of tertiary-base olefines from hydrocarbon mixtures produced by cracking petroleum oil and containing paraffin and olefine hydrocarbons of the same number of carbon atoms to the molecule, comprising reacting the hydrocarbon mixture with sulfuric acid of an acid concentration and at a temperature and for a time whereby substantially all of the tertiary olefine content is substantially instantaneously polymerized, without substantially polymerizing secondary olefines present and separating from the acid liquor a substantial proportion of the polymers present.

20. The process for. the selective removal of tertiary-base olefines from hydrocarbon mixtures produced by cracking petroleum oil and containing parafiin and olefine hydrocarbons of the same number of carbon atoms to the molecule, comprising reacting the hydrocarbon mixture with acid of an acid concentration and at a temperature and for a time whereby substantially all of the tertiary olefine content is substantially instantaneously polymerized, without substantially polymerizing secondary olefines present and separating from the acid liquor a substantial proportion of the polymers present.

21. The process of reacting a mixture of olefines with diluted sulfuric acid of a concentration and at a temperature and for a time whereby selective polymerization of part of the olefines takes place substantially instantaneously during initial contact, separating from the acid liquor a substantial proportion of the resulting polymers and then bringing the separated acid liquor into contact with an additional quantity of olefine.

22. The process of reacting a mixture of olefines with diluted sulfuric acid of a concentration and at a temperature and for a time in discontinuous liquid phase whereby selective polymerization of part of the olefines takes place substantially instantaneously during initial contact, separating from the acid liquor a substantial proportion of the resulting polymers and then bringing the separated acid liquor into contact with an additional quantity of olefine.

23. The process of reacting a mixture of olefines, produced by cracking petroleum products, with sulfuric acid of a given strength and at a temperature and for a time whereby selective polymerization of part of the olefines takes place substantially instantaneously during initial contact, separating from the acid liquor a substantial proportion of the resulting polymers and then bringing the separated'acid liquor into contact with an additional quantity of olefine.

24. The process of reacting a mixture of olefines with sulfuric acid of a given strength at an elevated temperature and for a time whereby selective polymerization of part of the olefines takes place substantially instantaneously during initial contact, separating from the acid liquor a substantial proportion of the resulting polymers and then bringing the separated acid liquor into contact with an additional quantity of olefine.

25. The process of reacting a mixture of olefines with hot sulfuric acid of a given strength and for a time whereby selective polymerization of part of the olefines takes place substantially l instantaneously during initial contact, separating from the acid liquor a substantial proportion of the resulting polymers and then bringing the separated acid liquor into contact with an additional quantity of olefine.

WILLIAM ENGS. RICHARD MORAVEC 

